Narrative ReviewHuman2026United States
Garment fit, scrotal thermoregulation, and male fertility outcomes: a narrative review.
Plain-language summary
This review looked at whether the underwear a man wears, tight versus loose, actually affects his fertility. The testicles work best a little cooler than the rest of the body, and the idea is that tight underwear traps heat. The authors gathered the human studies on underwear style and semen quality, plus lab studies on testicle heat, and summed them up in words rather than pooling the numbers. They found that tighter underwear can raise scrotal temperature a little, but the evidence that this meaningfully changes fertility is thin and mixed.
Key findings
- Tight-fitting underwear was linked to higher scrotal temperatures.
- Modest differences in semen parameters were found between briefs and boxers.
- No clear impact on pregnancy outcomes was observed.
How to analyze the study yourself
- Study type
- A narrative review synthesizes existing literature but does not conduct new analyses, making it useful for summarizing current knowledge while highlighting gaps.
- Population
- The review synthesized studies on men, focusing on underwear choice and its effects on scrotal temperature and fertility.
- Funding
- Not reported
- Watch for
- This review found that tight underwear can nudge scrotal temperature up, but there is not strong evidence it makes a real difference to fertility for most men. It is a small, cheap lever, so if you are trying to conceive, looser underwear is an easy step worth taking, just do not count on it as the fix.